A variety of software data (hereinafter referred to as a content) including audio data such as music, image data such as movies, game programs, and a variety of software programs is recorded as digital data on recording media including Blu-ray disk employing blue laser, a DVD (digital versatile disk), an MD (Mini Disk), and a CD (compact disk). The Blu-ray disk employing blue laser has a high recording density and records video contents of a large amount-of data as high image quality data.
The variety of information recording media with the digital content recorded thereon is supplied to users. Each user plays back and uses the content on the user's own personal computer, disk player, etc.
The distribution right of a majority of contents including music data and video data is held by the creators or sellers of the contents. A certain limitation is imposed on the distribution of the contents, in other words, an authorized user only has the right to use the corresponding content, and unauthorized copying of a content is typically inhibited.
Digital recording apparatuses and recording media are currently in widespread use. A digital recording apparatus and a digital recording medium allow a movie or audio to be repeatedly recorded or replayed without any quality drop involved. Unauthorized copied contents are distributed over the internet, contents copied on a CD-R, so-called pirated disk, are distributed, and unauthorized copied contents stored on a hard disk in a computer are used. Use of unauthorized copied contents becomes a concern.
A large capacity recording medium, such as a DVD or a recently developed recording media using blue laser, can digitally record a large amount of data as large as a single movie to several movies in one piece of medium. To protect copyright of a content from unauthorized copying becomes more and more important considering that video information is easily recorded as digital information. A variety of techniques for protecting digital data from unauthorized copying is incorporated in a digital recording apparatus and a recording medium.
For example, the content scramble system is used in DVD disk players. In the content scramble system, video data or audio data is recorded on a DVD-ROM (read only memory) in the encrypted form thereof. By descrambling the data, the content is played back.
In the descrambling process, a key for decrypting the encrypted data is provided to a licensed DVD player only. A license is given a DVD player that is designed to follow an operation rule in which no authorized copying is performed. The licensed DVD player decrypts the encrypted data on the DVD-ROM using a given key, thereby replaying an image or sound from the DVD-ROM.
Since unlicensed DVD players hold no particular data, such as the key for decrypting the data, the encrypted data recorded on the DVD-ROM cannot be decrypted. In the content scramble system, any DVD player failing to satisfy licensing requirements cannot replay digital data from the DVD-ROM. Unauthorized copying is thus prevented.
In the content scramble system, workload increases on an information processing apparatus as a user device executing a playback process. There are many known content scramble systems in which a scramble method has already been deciphered and is available via communications means such as the Internet. Once the scramble method is deciphered, the contents are played back and copied using unauthorized descramble process. The copyright of the content and the right to use the content are thus violated.